There are many coal seams throughout the world that are conventionally (presently) considered uneconomical to mine because of the thinness of the seam. However, according to the method of the present invention, in utilizing apparatus according to the present invention, it is possible to economically mine such seams utilizing split loading mining techniques. According to the invention, it is possible to economically mine a thin coal seam for example, one having a thickness of between about one and four feet, e.g., about 2-33 feet) by cutting the coal, and then cutting into the overburden or the bore floor in order to enlarge the bore, since it is possible to automatically distinguish between masses of conveyed cut material and to readily separate the mined coal from the rock overburden or the like. This is preferably accomplished, according to the invention, by utilizing a conventional radioisotope gauge that is normally employed to distinguish between ash contents of different coals.
According to one aspect of the present invention, a method of split load mining a coal seam having a thickness (e.g., between about 1-4 feet) less than that conventionally considered economical to mine, utilizing a cutting element having an operative cutting dimension approximately equal to the coal seam thickness, is provided. The method comprises the following steps:
(a) Cutting into essentially only the coal seam with the cutting element to form a mine bore having a mouth. PA1 (b) Conveying cut coal from the bore to the mouth. PA1 (c) Periodically interrupting steps (a) and (b) to cut into overburden or the bore floor to enlarge the bore to provide adequate clearance distance for the mining operation, thereby generating non-coal cut material. PA1 (d) Conveying the non-coal cut material from the bore to the mouth. PA1 (e) Substantially continuously automatically conveying the cut coal and non-coal cut material in a common path away from the bore mouth. PA1 (f) While practicing step (e), substantially continuously automatically analyzing at least one property of the conveyed material that distinguishes coal from non-coal, to determine whether conveyed material at a first location along the common path is primarily coal or primarily non-coal; and PA1 (g) In response to step (f), automatically diverting primarily coal to a second location, and diverting primarily non-coal to a third location.
In the practice of the method described above, step (f) is preferably practiced by analyzing the ash content of the material and utilizing a conventional radioisotope gauge. Step (e) is preferably practiced by providing a common conveyance path extending upwardly from the bore mouth at an angle greater than about 1 degree and less than about 17 degrees (e.g. about 10.degree.), and utilizing a conveyor belt. Step (c) is preferably practiced by cutting into rock overburden with a cutting drum, and step (d) is practiced by conveying cut rock. Step (g) is preferably practiced by moving a diverting vane to and from a first position which diverts conveyed material from the end of the conveyor belt to the second location on the first side of a vertical barrier, and a second position which diverts conveyed material from the end of the conveyor belt to the third location on the second side of the vertical barrier.
According to another aspect of the present invention, apparatus for mining coal and separating mined coal from non-coal (e.g., rock overburden) material transported from the same mine as the coal, is provided. The apparatus according to the invention comprises:
A conveyor for automatically substantially continuously conveying both coal and non-coal material from the mine in a common conveyance path.
Means for continuously automatically analyzing at least one property of the conveyed material on the conveyor that distinguishes coal from non-coal, to determine whether conveyed material at a first location along the conveyance path is primarily coal or primarily non-coal.
Diverting means at the end of the conveyor conveyance path remote from the mine; and
Means responsive to the automatically analyzing means for controlling the diverting means to automatically divert primarily coal to a second location, and to automatically divert primarily non-coal to a third location.
Preferably in the apparatus described above the conveyor comprises a conveyor belt which is disposed extending upwardly from the mine at an angle between about 0 and 20 degrees, and the automatic analyzing means comprises a radioisotope gauge for analyzing the ash content of the material. The diverting means preferably comprises an inverted Y-shaped conduit section having first and second hollow legs extending from a hollow stem at the top end of the conveyor belt, and a diverter vane within the conduit section mounted for rotation about a substantially horizontal axis by a shaft. The diverter vane is movable between a first position in which it blocks off the first hollow leg from the stem, and a second position in which it blocks off the second hollow leg from the stem. The diverter means also preferably comprises a vertical barrier disposed below the diverter stem and defining the second location on one side thereof and the third location on an opposite side thereof. The control means preferably comprises a motor or linear actuator operatively connected to the shaft for effecting rotation of the shaft about the substantially horizontal axis, and a computer operatively connected to the motor or linear actuator and radioisotope gauge.
It is the primary object of the invention to provide an effective method for economically mining coal seams having a thickness less than that conventionally considered economical to mine, and to provide simple yet effective apparatus for facilitating that method. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the invented claims.